The present invention relates to the field of receivers for receiving mixed television broadcast signals of interlace scanning system signals and progressive scanning system signals.
Digital broadcasting is becoming more common. In 1994, for example, the US started a multiple channel satellite digital broadcasting service, and similar services were started in 1996 in Japan and Europe. The use of digital video equipment is also advancing in packaged media systems including Digital Video Disks (DVDs) and Digital Video Cassettes (DVCs).
Digital broadcasting with increasingly higher image quality is also under development. For example, Advanced Television (ATV), planned in the US, is based on 18 standard video formats consisting of 4 interlace scanning system video formats and 14 progressive scanning system video formats. The progressive scanning system, which has good compatibility with personal computers, is given more importance.
In Japan, field tests for satellite transmission of 525p signals (progressive scanning of 525 scanning lines every {fraction (1/60)} sec) were carried out by the Japan television broadcast network in 1995 and 1996. Progressive scanning system signals have the same number of scanning lines as current broadcasting systems, but the resolution of moving pictures is greater, and therefore a great improvement in picture quality is expected. This system is scheduled to be commercialized in fiscal 1997.
For digital television broadcasting, for example, 525p with high picture quality and conventional 525i (2:1 interlace scanning of 525 scanning lines every {fraction (1/30)} sec, i.e., conventional NTSC) are expected to be mixed and broadcast on the same channel. A receiver of the prior art for the progressive scanning system which is capable of receiving such broadcasts converts input video signals of the interlace scanning system to signals of the progressive scanning system, and outputs only video signals of the progressive scanning system from the output terminal of the receiver. When video signals of the progressive scanning system are input, the receiver outputs the video signals in unmodified form, i.e., without converting them.
On the other hand, a receiver of the prior art for the interlace scanning system, which is capable of receiving mixed broadcast signals, converts input video signals of the progressive scanning system to signals of the interlace scanning system, and outputs only video signals of the interlace scanning system from the output terminal of the receiver. When video signals of the interlace scanning system are input, the receiver outputs the video signals in an unmodified form. i.e., without converting them. In other words, receivers of the prior art are capable of outputting signals in only a single output format.
FIG. 12 shows an example of a receiver of this type. In FIG. 12, a block diagram of major parts of the receiver is combined with a television set 62.
When the receiver receives mixed broadcast signals containing progressive scanning system signals (hereafter referred to as the p signal) and interlace scanning system signals (hereafter referred to as the i signal), the video signals are input through a video signal input terminal 59. A p-i scan converter 60, the major component of the receiver, has the function of converting the p signal to the i signal.
If the television set 62 is compatible with the existing interlace scanning broadcasting, such as NTSC, an i video signal output terminal 61 of the receiver, for outputting the i signal, and an external input terminal 63 of the television set 62 are connected. An external input terminal 64 of the television set 62 and the video signal input terminal 59 of the receiver are also connected. External input terminals 63 and 64 are optionally provided in the television set 62.
With the above connections, the p-i scan converter 60 converts the p signal to an i signal if the video signal input to the receiver is the p signal, and the video signal converted to the i signal is output from the external input terminal 63 of the television set 62 via the i video signal output terminal 61. The p-i scan converter 60 does not operate if the input video signal is the i signal.
If a broadcast signal is the i signal, that signal is directly input to the television set 62 because the external input terminal 64 of the television set 62 and the video signal input terminal 59 are connected.
With the above connections, the user desirably switches the external input terminals 63 and 64 of the television set every time the broadcasting system is switched if both the p signal and i signal are broadcast. In an extreme case, for example, the external input terminals may be expected to be switched every 10-sec in a commercial film.
Moreover, a monitor, television set, video tape recorder, and other equipment, which may be connected to the receiver, have their own switchover function, and accordingly a variety of switching systems exist for the various external input signals. If more than two pieces of external equipment are connected, operation may become even more complicated.
A receiver of the present invention is capable of receiving mixed video broadcast signals having a plurality of different formats, converting received video signals into video signals having a format different from that of the received signals, and outputting both the converted signals and the unconnected received video signals.
The receiver of the present invention is further capable of receiving mixed video broadcast signals in a plurality of different formats, converting the received video signals into video signals having a plurality of different formats from that of the received video signals, and outputting both the received video signals and a plurality of converted video signals.
Furthermore, the receiver which receives mixed broadcast video signals in a plurality of different formats comprises a plurality of conversion means for converting the received video signals into video""signals having a different signal format from the format of the received signal, and a plurality of switching means for switching between the received video signals and signals converted into the plurality of different formats; and outputs both the received video signals and the converted video signals.
The user may be able to connect a television set compatible with either the interlace scanning system or the progressive scanning system, to a corresponding output terminal for interlace scanning video signals or an output terminal for progressive scanning video signals provided on the receiver. This allows the user to watch television without being conscious of the switching between the different broadcasting systems-even if programs are broadcast in both the progressive scanning system and the interlace scanning system.